Statics

• Declared without the initializer expression
• Both immutable and mutable access are unsafe as it may have uninitialized or invalid value

Examples

use std::ffi::*;

extern "C" {
    /// index of the next element to be processed in argv by getopt
    static optind: c_int;
}

fn main() {
    assert_eq!(unsafe { optind }, 1);
}

Caveats

• An immutable static must be initialized before any Rust code is executed

References

• https://doc.rust-lang.org/reference/items/external-blocks.html#statics
• https://doc.rust-lang.org/nomicon/ffi.html#accessing-foreign-globals